This invention is related to improvements in a double-sided flexible disc drive apparatus for writing and reading digital information, associated with an electronic computer, into and out of both surfaces of a flexible magnetic recording disc medium. Particularly, the invention is related to a device for softly loading a flexible magnetic recording disc with a magnetic head or heads and softly unloading the magnetic head or heads from the flexible magnetic recording disc medium.
Conventional double-sided flexible disc drive apparatus have comprised an interchangeable flexible magnetic recording disc medium rotatably disposed therein, a pair of opposite magnetic heads held by a pair of upper and lower spring loaded arms respectively and operative to place the magnetic recording disc therebetween, a movable carriage for pivotally carrying the upper and lower arms, and a lifting arm connected to the upper arm to raise and lower simultaneously the upper and lower arms and the opposite magnetic heads toward and away from the magnetic recording disc medium.
In an inoperative state or on standby, the lifting arm is raised by a bail plate operatively coupled to an armature of an electromagnet to prevent the magnetic heads from contacting the magnetic recording disc medium. The armature is arranged to ascend by a return spring disposed on the electromagnet when the latter is not energized. In operation, however, the electromagnet is energized causing the bail plate to approach the magnetic recording disc medium thereby releasing the lifting arm from the bail plate. At this time, the upper and lower arms approach the record disc by means of the biasing of force springs coupled thereto until the magnetic heads contact the respective opposite surfaces of the recording disc medium. At that time the magnetic heads have tended to strike against the opposite recording surfaces of the disc medium causing damage to the latter recording medium surface.
It is already known that such damage to the magnetic recording surface can be alleviated by controlling the speed at which each of the magnetic heads contacts and strikes the recording disc medium, to a suitable magnitude.
One known type of means for alleviating damage to the magnetic recording surfaces as described above is a piston slidably fitted into an air cylinder disposed within a mounting casing to form a dash-pot or an air damper. The mounting casing has been fixedly secured to the movable carriage and the piston includes a piston rod connected to the upper arm adjacent to the associated magnetic head. When the upper arm descends toward the magnetic recording disc medium due to the energizing of the electromagnet, the air damper provides a braking force so as to control the descending speed of the upper arm resulting in the minimization of damages to the magnetic recording disc medium. However, this air damper has increased the mass of the carriage which must be rendered as light as possible.
Accordingly, it is an object of the present invention to provide a new and improved magnetic disc soft loading and unloading device including an effective means for preventing a magnetic recording medium involved from damaging while eliminating the disadvantages of the prior art practice and to provide a device suitable for use with a double-sided flexible disc drive apparatus.
It is another object of the present invention to provide a new and improved magnetic head soft-loading and unloading device of the type described in the preceding paragraph including a simplified mechanical portion and an electronic circuit forming a negative feedback system which can control the speed at which the magnetic recording medium is loaded with an associated magnetic head or at which the magnetic head is unloaded from the magnetic recording medium to thereby decrease the damage to the magnetic recording medium.